i try to bind value into ValidationErrors.

i have this method:

  isUniqueEmail(control: FormControl): ValidationErrors {
    if (control.value != null) {
        console.log(control.value)
        if(control.value == this.foundEmail){
          console.log("found one");
          return {isUniqueEmail: true}
        }else{
          return null;
        }
      }
  }

this method check if control.value (email typing) equal email stored in global variable this.foundEmail then we have duplicate email.

My problem is: i can retreive data from foundEmail in this method because this method is private.

this method is located inside export class exampleComponent implements OnInit.

Error: ERROR TypeError: Cannot read properties of undefined (reading 'foundEmail')

But i check i have data into foundEmail

CodePudding user response：

The validator function gets called from the FormControl so its context is not bound to the class you're defining the method on. You need to manually bind isUniqueEmail() to this.

Two options:

1. Use bind() when defining the FormControl:

   name: new FormControl("", [
       this.isUniqueEmail.bind(this),
   ]),
   

2. Define your validator as arrow function:

isUniqueEmail = (control: FormControl) => {
    if (control.value != null) {
        console.log(control.value)
        if(control.value == this.foundEmail){
          console.log("found one");
          return {isUniqueEmail: true}
        }else{
          return null;
        }
      }
  }